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|Hair color||Purple with muted lavender streaks|
Yoshiharu Hisomu (日染 芳春, Hisomu Yoshiharu) is one of the seven main Kiznaivers. He is the 'Immoral'.
Hisomu is a handsome yet pain-loving masochistic teen. He has mid-length, heavily layered purple taupe hair with grey highlights. His eyes are of a golden olive color, and he has multiple piercings on both ears and a single labret piercing below his lip. He is constantly seen with bandages covering both his neck and wrists. Hisomu's clothes always look quite worn down and are paired with flip flops. He appears to be around 180cm tall. It has been stated by several characters in the anime that he is a "natural hot guy", unlike Yuta, who had to work to look how he is now.
It seems that Hisomu is able to withstand and enjoy physical pain, much like Katsuhira's high pain tolerance leading to him not feeling physical pain at all. In episode 9, it is shown he was the only member (saving Katsuhira) who was able to talk after they were able to hear each other's "thoughts".
He is shown to be a masochist, and is quite eccentric throughout the whole show. Being a masochist, he gets aroused when feeling or thinking about pain. It has also been suggested that he is suicidal. When around Nico it is shown that he will occasionally act childish, and he will also occasionally do this regularly. It is also known that he cannot swim. Besides this, not much is known about him in general, as he is considered an enigma. Although he seems harmless and spends most of his time, smiling innocently, he is usually blunt and unnerves the other Kiznaivers of his group.
Hisomu took a liking to Katsuhira the moment their eyes met in episode 3. He, along with Nico, are shown to support Katsuhira when times get tough within the Kiznaiver group. The both of them are shown to be on friendly terms with each other throughout the whole series.
These two are on friendly terms. Even though in episode 3 Nico calls Hisomu a 'scallywag', she appears to still want to befriend him. Nico and Hisomu are the first of the group to establish with Katsuhira that they still want to be friends even after the Kiznaiver missions in the summer. At the end of the series, Hisomu notes that Nico is actually pretty mature.
Among the rest of the Kiznaivers, Hisomu doesn't necessarily like Noriko and Hisomu is indifferent towards Noriko. He is mostly blunt or generally polite when around her, just like he is with everyone else.
- Hisomu cannot swim.
- Hisomu is a masochist.
- He is the only Kiznaiver to not fall in love with someone.
- He seems to enjoy sweet things, briefly mentioning that he prefers Lumonde Bourbon over Baum Rolls in episode 4. He has also asked if he could have caramel ribbon icecream when the main characters were about to have some from a vending machine.